Touschek with AdA in Orsay and the first direct observation of electron-positron collisions

Abstract

We describe how the first direct observation of electron-positron collisions took place in 1963-1964 at the Laboratoire de l'Acc\'el\'erateur Lin\'eaire d'Orsay, in France, with the storage ring AdA, which had been proposed and constructed in the Italian National Laboratories of Frascati in 1960, under the guidance of Bruno Touschek. The obstacles and successes of the two and a half years during which the feasibility of electron-positron colliders was proved will be illustrated using archival and forgotten documents, in addition to transcripts from interviews with Carlo Bernardini, Peppino Di Giugno, Mario Fascetti, Francois Lacoste, and Jacques Ha\"issinski.